Precise ligand engineering of Ir(III)‐based photosensitizer with aggregation‐induced emission for image‐guided photodynamic therapy

Abstract Photodynamic therapy (PDT), which relies on the production of reactive oxygen species (ROS) induced by a photosensitizer to kill cancer cells, has become a non‐invasive approach to combat cancer. However, the conventional aggregation‐caused quenching effect, as well as the low ROS generation ability of photosensitizers, restrict their biological applications. In this work, a new Ir(III) complex with a dendritic ligand has been strategically designed and synthesized by ingenious modification of the ancillary ligand of a reported Ir(III) complex ( Ir‐1 ). The extended π‐conjugation and multiple aromatic donor moieties endow the resulting complex Ir‐2 with obvious aggregation‐induced emission (AIE) activity and bathochromic emission. In in vitro experiments, importantly, Ir‐2 nanoparticles exhibit the excellent photoinduced ROS generation capabilities of O 2 •− and 1 O 2 , as well as excellent biocompatibility and the lipid droplets (LDs) targeting feature. This study would provide useful guidance to design efficient Ir(III)‐based photosensitizers used in biological applications in the future.